What is the best way to get "last sync timestamp"?

I plan to use flow + monitor to sync entries from system A to system B. Target to run 2 sync/day (12 hr duration). Below are my log and i noticed it’s not 100% a 12 hr for each run, there is a couple of mins delay. If that’s the case, is it possible for us to get the accurate “last sync time”? if i am using the script to control, it’s potentially miss out some entries if it’s beyond sync duration

e.g, changes made 12.01AM, then in next 12 hrs, it run at 12.05PM, if my code -12hr, the last sync will be derive as 12.05AM (12.01AM changes missed out)